1. Field of the Invention
The present invention relates to a control system for an internal combustion engine with a turbo supercharger, and more specifically, to a control system for an intake system for the engine.
2. Description of the Prior Art
There has been known a dynamic supercharger utilizing a pressure oscillation or resonance effect provided by intake gas, a valve timing control device for controlling valve timings of intake and/or exhaust valves and a mechanical and turbo super charger which improves intake gas charging efficiency. Further, it is also known to provide a first intake condition in which the engine is controlled to improve the intake gas charging efficiency in a lower engine speed condition and a second intake condition in which the engine is controlled to improve the intake gas charging efficiency in a higher engine speed condition. The first and second intake conditions are selectively established in accordance with the engine speed to obtain an improved intake gas charging efficiency over a greater range of the engine speeds. In addition, it has been proposed to combine two or more the above control systems for further improving the intake gas efficiency. For example, Japanese Patent Public Disclosure No. 59-164408, laid open to the public in 1984, discloses an engine provided with both the turbo supercharger and the dynamic supercharger.
In an engine with a turbo supercharger, it is desirable to suppress an excessive increase of the supercharging pressure of the intake gas in the lower engine speed condition in order to prevent knocking. It should, however, be noted that there is no conventional engine with both a turbo supercharger and another system for improving the charging efficiency of the intake gas which can improve the charging efficiency, preventing the knocking of the engine, in a broader range of engine operating conditions.